Study on the Formation and Disassociation Process of Hydrate in Porous Media by Permittivity Dispersion Measurement

To develop a more efficient and environmentally friendly exploitation and production method of gas hydrate, a better understanding of the formation and disassociation process mechanism of gas hydrate in porous media is indispensable. The permittivity spectra of gas hydrate differs from water, oil, ice and gas, and thus measurement of its permittivity properties is a potential approach to detect hydrate existence and content. In this study, THF (tetrahydrofuran) was used as the hydrate former. The permittivity dispersion of hydrate in quartz sand was measured with open-ended coaxial method in the processes of formation and disassociation at a wide radio frequency band from 1MHz to 3GHz. From the dielectric measurements, the hydrate concentration in the porous media was identified with dispersion properties, and the characteristic of the permittivity response upon the hydrate formation and dissociation were also provided. Moreover, by applying dielectric mixing models, the fractions of the solution and hydrate could be estimated. These results implied that the permittivity dispersion could be an effective monitor for the formation and disassociation of the hydrate, and hydrate content could be evaluated in real time with complex permittivity spectra.